1. Field of the Invention
The invention relates to an apparatus for processing substrates, such as semiconductor substrates, and more particularly, to an apparatus for distribution of process fluids over a substrate.
2. Description of the Related Art
Semiconductor processing systems generally include a process chamber having a pedestal for supporting a substrate, such as a semiconductor substrate, within the chamber proximate a processing region. The chamber forms a vacuum enclosure defining, in part, the processing region. A gas distribution assembly or showerhead provides one or more process gases to the processing region. The gases are then heated and/or energized to form a plasma which performs certain processes upon the substrate. These processes may include deposition processes, such as chemical vapor deposition (CVD), to deposit a material on the substrate or an etch reaction to remove material from the substrate, among other processes.
In processes that require multiple gases, the gases may be combined within a mixing chamber that is then coupled to the gas distribution assembly via a conduit. For example, in a conventional thermal CVD process, two process gases are supplied to a mixing chamber along with two respective carrier gases where they are combined to form a gaseous mixture. The gaseous mixture may be introduced directly to the chamber, or may travel through a conduit within an upper portion of the chamber to the distribution assembly. The distribution assembly generally includes a plate having a plurality of holes such that the gaseous mixture is evenly distributed into the processing region above the substrate. In another example, two gases pass through the distribution assembly separately, and are allowed to combine before reaching the processing region and/or the substrate. As the gaseous mixture enters the processing region and is infused with thermal energy, a chemical reaction occurs between the process gases, resulting in a chemical vapor deposition reaction on the substrate.
Although it is generally advantageous to mix the gases prior to release into the processing region, for example, to ensure that the component gases are uniformly distributed into the processing region, the gases tend to begin reduction, or otherwise react, within the mixing chamber or distribution plate. Consequently, deposition on or etching of the mixing chamber, conduits, distribution plate, and other chamber components may result prior to the gaseous mixture reaching the processing region. Additionally, reaction by-products may accumulate in the chamber gas delivery components or on the inside surface of the distribution plate, thus generating, and/or increasing the presence of, unwanted particles.
Temperature control of the gases as they are released into the processing region is advantageous for controlling the reactivity of the gases. For example, cooling the gases can be helpful in controlling unwanted reactions prior to release into the processing region. The gases refrain from reacting until they come into contact with a heated substrate. In other circumstances, heating of gases may be necessary. For example, hot gas purging or cleaning may help remove contaminants from a processing chamber. Thus, integrating a temperature control aspect into a gas distribution plate is useful.
Therefore, there is a continuing need for a gas distribution device that delivers at least two gases into a processing region without co-mingling of the gases prior to reaching the processing region.